Drill bit



Patented Apr. 16, 1940 UNITED STATES 1mm. nrr I Thomas H. Stanclifl, Houston, Tex, minor to Reed Roller Bit Company, Houston, Tex., a

corporation of Texas Application March 20, 1939, Serial No. 262,902

7 Claims.

This invention relates to drill bits and has for its general object the provision of an improved construction for mounting roller cutters thereon.

The particular embodiment illustrated has reference to a bit of the type known as a cross roller bit wherein certain of the roller cutters are mounted on an axis transversely with respect to the bit head. When cutters are so mounted, the

, cutters on opposite sides of the axis of the bit head have a tendency to move radially outwardly along their shafts whenin operation. It is necessary, therefore, not only to provide radial bearings for these cutters but also thrust bearings to take the end thrust referred to. It has been proposed that the shaft for mounting these outters be made in two parts so that the thrust bearings may be properly positioned and the cutters placed in position on the shaft sections by move- 7 ment of each cutter on its shaft section from that end which isadapted to lie most closely adjacent the axis of the bit head. The shaft sections are then joined together at their adjacent ends.

It is an object of this invention to provide such a means which will not involve the use of welding or the like in joining the sections together but which will serve to firmly and'rigidly hold the shaft sections in alignment with each other.

Other objects and advantages of this invention will become apparent from the following description, taken in connection with the accompanying drawing, wherein is set forth by way of example one embodiment of this invention.

In the drawing:

Fig. 1 shows a view partly in vertical cross section through a bit constructed in accordance with invention.

Fig. 2 is a fragmentary view showing a modification.

the numeral l designates the body of the bit head having a threaded portion 2 at its upper end for engagement with a drill collar on the lower end of the drill stem and having a fluid passage 3 therein through which is adapted to be supplied a drilling fluid, the same being directed against the cutters by means of openings at properly spaced points through the web 4.

The bit head is provided at four opposed points with downwardly and laterally extending lugs 5 and 6, respectively, the lugs 6- being adapted for the support of spindlesfor carrying the customary side cutters 1 and for serving as a support 55 for a bridge 8.

Referring more particularly to the drawing,

To the lugs are adapted to be welded downwardly extending support members 9 which are formed integral with the outward extremities Ill and II of the shaft sections l2 and I3. The adjacent ends l5 and I6 of these shaft sections are 5 adapted to be inserted into a bushing I1 into which they fit with a shrink fit so that the ends of these shafts will beheld firmly and rigidly with respect to each other.

This bushing I1 is adapted to fit snugly but not tightly within an opening formed in the bridge 8 as illustrated so that it will be supported by said bridge. It may however be fitted into the bridge with a shrink fit or pressed in, if. desired.

Surrounding the respective shaft sections l2 and I 3 are cutters l8 and I9. Each of these cutters has a relativelylarge inner roller bearing race for receiving the roller bearings 20 and 2|, respectively, adjacent the opposite arms 9. The shaft sections l2 and l 3 have corresponding bearing races for these roller bearings and have also at a position radially inwardly from these bearing races, outwardly facing bearing races 22 and 23, respectively, for sets of ball thrust bearings 24 and 25. Inwardly from the ball thrust bearings and of smaller diameter than the ball thrust bearings are additional sets of radial roller bearings 26 and 21, respectively. The cutters l8 and I9 are formed with outwardly facing ballraces forreceiving the ballthrust bearings, respectively, and with roller races of smaller diameters than the ball races for receiving the radial roller bearings 26 and 21. 4

The method of assembly of the. drill bit just described is as follows:

The main body of the drill bit will first be formed as set forth, after which the side cutters I with the bridge 8 will be properly secured in position in any desired manner." The various radial and thrustbearings willthen be placed in their respective positions about their shaft sections l2 and I3 and. the cutters l8 and i9 placed over these shaft sections from the ends l5 and I6 thereof respectively. The bushing IT will then be heated or otherwise expanded and will then 'be inserted into the opening in the bridge 8, after which the ends l5 and 16 of the shaft sections will be inserted therein into their proper position. The supporting arms 9 will then be welded, as shown at 28 to the body I in such position as to hold the shaft sections in proper relation with respect to each other and with relation to the respective other parts of, the drill bit. when the bushing l1 cools or is otherwise caused to contract, it will shrink upon the-ends l5 and I6 and serve to firmly and rigidly grip these ends to join them together and hold them in proper position with respect to each other. No welding or other securing means is required which might weaken or otherwise injure the bridge or the shaft sections for the purposes for which they are intended.

In Fig. 2 the cutters i8 and H! are shown mounted on two shaft sections I2 and i3 which are similar to the shaft sections l2 and I3 with the exception that the shaft section I2 is formed with an enlarged portion l1 which is partly hollowed out to receive the end l6 of the other shaft section with a shrink fit. This enlarged portion I1 is itself fitted into the opening in the bridge 8. The effect of this difierence in construction is only that instead of a separate collar I! as shown in Fig. 1, the corresponding member is formed integrally with one of the shaft sections.

It will be appreciated that various changes may be made in the details of the construction without departing from the spirit or scope of this invention, it being understood that this invention is to be limited only by the prior art and by the terms of the appended claims.

It will further be understood that instead of a so-called shrink fit produced by heating the socket member or cooling the pin member before placing them together and then letting them resume their normal temperature, the parts might be placed together when they are the same temperature. It will also be appreciated that the collar I! or the end portion l1 may be pressed into or mounted within the opening in the bridge with a shrink fit, if that be found desirable.

It will be understood, therefore, that wherever the words shrink grip or the equivalent are used in the claims of this application they are to be taken as including a press fit or other equivalent of a shrink grip.

From the foregoing it will be seen that a simplified and yet wholly efficient means has been provided for carrying out the objects of this invention and for properly supporting the cross roller cutters of a drill bit.

Having described my invention, I claim:

1. A drill bit comprising a head, cross roller cutters carried by said head on an axis extending transversely with'respect to said head, and means for supporting said cross roller cutters comprising a shaft formed in two sections, means for supporting the remote ends of said sections from said body, and means engaging the adjacent ends of said section with a shrink grip for joining them together.

2. A drill bit comprising a head, cross roller cutters carried by said head, and means for supporting said cross roller cutters from said head, said means comprising a shaft formed in two sections, means for supporting the remote ends of said shaft from said body, and means comprising a collar surrounding the adjacent ends of said sections and engaging them with a shrink grip to join them together.

3. A drill bit comprising a body, cross roller cutters carried by said body, and. means for supporting said cross roller cutters, said means comprising a shaft formed in a plurality of sections, each of said sections adapted to rotatably support one of said cutters, means for supporting the remote ends of said sections from said body and means for joining with a shrink grip the adjacent ends of said sections.

4. A drill bit comprising a body, cross roller cutters carried by said body, and means for supporting said cross roller cutters, said means comprising a shaft formed in a plurality of sections, each of said sections providing support for one of said cutters, means for supporting the outer ends of said section from said body, means joining the inner ends of said sections together with a shrink grip and means for supporting said joining means from said body.

5. A drill bit comprising a body, cross roller cutters carried by said body, and means for supporting said cross roller cutters, said means comprising a shaft formed in a plurality of sections, each of said sections providing support for one of said cutters, means for supporting the outer ends of said section from said body, means joining the inner ends of said sections together with a shrink grip and a bridge extending across the lower end of said body and engaging said joining means to support the same from said body.

6. A drill bit comprising a head, cross roller cutters carried by said head on an axis extending transversely with respect to said head, and means for supporting said cross roller cutters comprising a shaft formed in two sections, means for supporting the remote ends of said sections from said body, and means integral with one of said sections and having a part adapted to engage the adjacent end of the other section with a shrink bit for joining said sections together.

7. A drill bit comprising a head, cross roller cutters carried by said head on an axis extending transversely with respect to said head, and means for supportingsaid cross roller cutters comprising a shaft formed in two sections, means for supporting the remote ends of said sections from said body, one of said sections having a socket adjacent end of the other section with a shrink grip for joining said sections together.

THOMAS H. STANCLIFF.

-formed on its inner end adapted to receive an 

